1. Field of the Invention
The present invention relates to a diaphragm chuck for a machine tool.
2. Description of the Related Art
Such diaphragm chucks are generally known. For example, a diaphragm chuck is known from the published German patent document DE 1 652 942 B which has two groups of chuck jaws which are situated at an axial distance from one another and which are each mounted on a diaphragm for chucking the workpiece, the diaphragm chuck also having an air pressure regulator for unchucking the workpiece. The diaphragm chuck is operated with compressed air in such a way that for unchucking the chuck jaws, compressed air is guided through a channel in the chuck housing, thus causing deformation of the clamping diaphragms. The chuck jaws of one group of chuck jaws are swiveled outwardly, partially parallel to an axial direction, while the chuck jaws of the other group of chuck jaws are swiveled inwardly, partially antiparallel to the axial direction. A workpiece may subsequently be inserted into the diaphragm chuck up to a stop, or removed from the diaphragm chuck. As a result of a targeted pressure reduction in the diaphragm chuck, the chuck jaws are swiveled back, so that a workpiece situated in the diaphragm chuck is securely clamped between the chuck jaws. It is disadvantageous that, due to the partially oppositely directed swiveling of the chuck jaws along the axial direction, the workpiece is slightly dislodged from the stop when the workpiece is gripped by the chuck jaws, so that the workpiece is acted on with play in the axial direction. The first and second groups of chuck jaws are also designed as one piece, so that a selective replacement of a single group of chuck jaws and/or individual, for example closing, chuck jaws is not possible.
Another diaphragm chuck is known from the published German patent application document DE 1 128 254 A, this diaphragm chuck having only a single clamping diaphragm. This has the disadvantage that the chucking power decreases as the axial distance between the chucking point and the diaphragm surface increases.